Method of manufacturing acrylic composite yarn

ABSTRACT

A METHOD OF MANUFACTURING AN ACRYLIC COMPOSITE FIBER WHICH CONTAINS PREDMINANTLY ARCYLONITRILE, CHARACTERIZED BY (A) SPINNING AN ACRYLIC COMPOSITE FIBER COMPOSED OF TWO OR MORE ACRYLIC POLYMER COMPONENTS TENDING T EXHIBIT DIFFERENT THERMAL BEHAVIORS AND ARRANGED ECCENTRICALLY ALONG THE ENTIRE LENGTH OF SAID FIBER, (B) STRETCHING SAID FIBER, (C) CRIMPING SAID FIBER MECHANICALLY, AND (D) FINALLY HEAT-TREATING SAID FIBER IN A RELAXED STATE WITH ITS MOISTURE CONTENT ADJUSTED TO BE FROM 50 TO 120% RELATIVE TO THE DRY WEIGHT OF SAID FIBER. THE PRESENT INVENTION ALSO PROVIDES FOR BIERS PRODUCED BY THE AFOREMENTIONED METHOD, HAVING COIL CRIMPS OF FROM 12.4 TO 17.3 CRIMPS PER 25 MM. OF FIBER LENGTH, AND HAVING A DEGREE OF CRIMPING OF BETWEEN 13.4 TO 20.9%.

United States Patent 3,644,609 METHOD OF MANUFACTURING ACRYLIC COMPOSITE YARN Kazumi Nakagawa and Keitaro Shimoda, Saidaiji, Japan, assignors to Japan Exlan Company Limited, Oska, Japan No Drawing. Continuation of abandoned application Ser. No. 817,249, Mar. 7, 1969, which is a continuation of abandoned application Ser. No. 566,238, July 19, 1966. This application Mar. 5, 1971, Ser. No. 121,526

Claims priority, applligation 1Jgapan, July 25, 1965,

Int. c1. Dtlld 5/22 US. Cl. 264-168 1 Claim ABSTRACT OF THE DISCLOSURE The present invention also provides for fibers produced by the aforementioned method, having coil crimps of from 12.4 to 17.3 crimps per 25 mm. of fiber length, and having a degree of crimping of between 13.4 to 20.9%.

This is a streamline continuation application of applicants copending application S.N. 817,249, filed Apr. 7, 1969, now abandoned, which in turn is a streamline continuation application of SN. 566,238, filed July 19, 1966, also now abandoned.

This invention relates to a method of manufacturing a composite fiber or yarn composed predominantly of acrylonitrile and possessing satisfactory crimping characteristics. A composite fiber in which two or more acrylic polymer components tending to exhibit different thermal behavior and arranged eccentrically along its entire length, would give rise to three-dimensional coil-shaped crimps on heating due to the difference in thermal shrinkage between or among said polymer components. The products made from such a composite fiber have not only a good bulk, but also a wool-like type hand. However, there is an extremely small shrinkability of the fiber resulting from its coil crimps, which rises from the difference in thermal shrinkage between or among its component materials, while adequate coil crimps may be developed when the fiber is heated in a relaxed state wherein it may freely move about, its free movement is usually prohibited when a great amount of the fiber is heat-treated in the form of a tow in the course of fiber-making. This is because of the fact that during the heating process the fiber is subject to various restrictive forces such as loads under its own weight, intimate contact of the adjacent monofilaments with each other, and tension forces, all of which prevent coil crimps from being successfully developed. Thus, such a composite fiber cannot possess adequate coil crimps, and, therefore, is not practically useful.

Various studies have been made of possible methods that might allow an acrylic composite fiber to develop adequate coil crimps in order to overcome the above-mentioned disadvantages. It has been found from these studies 'ice that satisfactory coil crimps may be produced in acrylic composite fibers if spinning dopes of two or more dissim- 1lar acrylic polymers, tending to exhibit different thermal behaviors are wet-spun into a composite fiber in which said two or more dissimilar polymer components are eccentrically arranged along its entire length; whereby the resulting fiber is stretched, oriented, and mechanically crimped, and the moisture content of the filament bundle subsequently properly adjusted; and wherein the fiber is finally heat-treated in a relaxed state under no tension.

Thus, this invention is concerned with a process for manufacturing an acrylic composite fiber from two or more dissimilar acrylic polymers tending to exhibit different thermal behaviors, eccentrically arranged throughout the length of said fiber, characterized by the steps of spinning dopes of such polymers into a composite fiber by the wet-spinning method, stretching and orienting the fiber, crimping it mechanically, adjusting the moisture content of said fiber to 50-120 percent and finally heattreating the fiber in relaxed state within the temperature range of C. to 135 C. Thus, in accordance with the present invention, a composite fiber possessing excellent mechanical properties and crimping characteristics may be prepared.

Since, besides mechanical crimps, spiral or coil-like crimps are also produced in the fiber, the final crimps are not comparable to the two-dimensional ones produced by mechanical crimping alone, but are augmented by said coil crimps to yield a three-dimensional configuration which is highly stable.

If mechanical crimping were omitted before the re laxed heat-treatment, it would be ditficult to attain adequate coil crimps from heat-treatment, and this is partly because of the extremely small shrinking capacity of the fiber in the formation of coil crimps derived from the aforesaid difference in thermal shrinkage alone between the components of the composite fiber, as and partly because since the filaments in the two which have not been mechanically crimped are straight and closely arranged. This means that the fibers are subject to various restrictive forces arising from compression among the adjacent filaments and other tension and cohesion forces which tend to limit the free movement of the filaments and, accordingly, prevent the development of adequate coil crimps. In contrast thereto, and in accordance with the present invention, when mechanical crimping is carried out before said heat-treatment in a relaxed state, the individual filaments within the tow are bent to relieve the intimacy of the filaments and tension and cohesion forces, thereby allowing the filaments to move freely in such a manner that coil crimps may develop easily as the fiber is heat-treated in a relaxed state. It is also necessary for the successful attainment of the objects of the invention, that the moisture content of the composite fiber after said mechanical crimping be at least 50% relative to the fiber, said level of moisture content greatly facilitating the development of satisfactory coil crimps on said relaxed heattreatment. The amount of coil-crimping would be inadequate if the moisture content of the fiber were below that level. However, if the fiber contains more than water, excessively fine crimps would be produced, so that the fiber would not only be prevented from developing a sufiicient bulk, but also might lose a considerable part of its otherwise woolly hand. It is possible to maintain the moisture content of the fiber within the range of 50% to 120% by immersing the tow in water before mechanical crimping and suitably adjusting the nip-roller pressure of the crimper or/and the outlet pressure of the stuffing box, or introducing water under pressure into the stuffing box after the fiber has passed through the nip-rollers, or spraying the tow with water after the tow is mechanically crimped, etc. The heat-treatment of the composite fiber in a relaxed state is generally conducted for about to minutes, preferably within the temperature range of 100 C. to 135 C. Below 100 C., the formation of coil crimps or the effect of relaxed heat-treatment would not show itself sufficiently. On the other hand, if the temperature exceeds 135 C., the crimped filaments would be excessively interlocked and/ or discolored.

The term acrylic polymers as used throughout this specification and claim refers to all polymers composed predominantly of acrylonitrile, inclusive of copolymers with vinyl monomers capable of copolymerizing with acrylonitrile and mixed polymers with other polymers.

The above-mentioned vinyl monomers or other compounds include, for example, vinyl acetate, vinyl chloride, vinylidene chloride, acrylic acid, methacrylic acid, and other acrylic acid derivatives, acrylamide, N-methylolacrylamide and its related derivatives, vinyl pyridine and its derivatives, and allylsulfonic acid, methallylsulfonic acid and their derivatives, as well as all other monomers copolymerizable with acrylonitrile.

This invention will be further described by way of the following examples, in which all percentages are by weight.

EXAMPLE 1 A copolymer composed of 91% acrylonitrile, 9% methyl acrylate, and 0.5% sodium methallylsulfonate as well as another copolymer composed of 89% acrylonitrile, 11% methyl acrylate, and 0.5 sodium methallylsulfonate are separately dissolved in 49% aqueous solutions of sodium rhodanate to prepare two dissimilar spinning dopes. Equal amounts of said dopes are extruded in an 8% aqueous solution of sodium rhodanate through a bi-component spinnerette to which two metering pumps are connected. The resulting tow is washed with water, and stretched in boiling water to 9 times its initial length. The spinnerette nozzle used above has 6532 orifices, each measuring 0.09 millimeter in diameter. The number of spindles is 20. Then, the fiber is dried in a highly humid atmosphere at the dry-bulb temperature of 120 C. and the wet-bulb temperature of 78 C. and then passed through tepid water at 80 C. The fiber is then mechanically crimped by a stufiing-box crimper under a nip-roller pressure of 2.0 kg./cm. and a stufiing-box pressure of 1.5 'kg./cm. The moisture content of the fiber after said crimping is The fiber bundle is then sprayed with water, and then heat-treated in a relaxed state in an oven using saturated water vapor at 120 C. for 5-10 minutes. Thereafter, the fiber is guided through a 0.8% aqueous solution of Teron N-5O oil (manufactured by Matsumoto Oils and Fats Co., Ltd.), followed by drying at 90 C. The fiber is finally inspected. The results are summarized in Table 1.

A D E F G H Number 01 crimps (per 25 mm.) 8.9 7.9 9.1 15.1 16.2 15.0 10.3 25.2 Degree of crimping (percent) 12.0 14.9 13.0 17.2 27.3 30.4 31.5 28.2

Using the staple of each fiber obtained under the conditions of Table 1, a spun yarn (2/36) is prepared.

In the spinning of these fibers, staples (A) to (G) could be spun satisfactorily, while (H) alone is difiicult to spin, for there arise many steps in the course of carding and uneven stretching in the course of the drawing process.

The spun yarns are made into hanks, which are then dyed with Serron Blue G (Du Pont) in a 0.5% OWF dyeing, which is heated from C. to 100 C. at the rate of 1 C. per minute and held at 100 C. for 30 minutes, at the end of which time the bath is cooled to 60 C. at the rate of 1 C. per minute. The dyed yarns are washed with water, finished, and dried. The characteristics of these dyed yarns are summarized in Table 3.

No'rE.In the above table 0. A and 1: denote satisfactory, fair, and poor hands, respeetix ely.

The bulkiness figures shown in Table 3 are arrived at as follows. The yarn is wound up on a cyindrical bobbin, a centimeters in radius and l centimeters in length, under a constant tension of 0.1 g./tex. to desired thickness at such a pitch as will give a yarn weight of 5.5 mg./cm. and the thickness of the winding (t cm.) and the total weight of the yarn (w gm.) are measured. From the results, the volume of the winding is calculated and the result is divided by the weight of the yarn. This reaction is expressed as follows.

bulkiness f It is to be understood that the greater the above value is, the bulkier the yarn.

The spun yarns made of fibers (A) and (B) which are not mechanically crimped before relaxed heat-reatment, as well as the spun yarn made of fiber (C), whose TABLE 1 This invention A B C D E F G H Mechanical crimping NOne Non 0118 D0118 Done Done Done Done Moisture content of fiber before relaxed heattreatment (percent) (relative to fiber) 0.8 113 25 53 Crimping characteristics:

N umber of crimps (per 25 mm.) 6. 8 7. 9 1 3 .4 14.5 16.9 17. 3 25. 2 Degree of crimping (percent) 1 .4 -3 2 3.4 17.3 19.3 20.0 21. 3

It will be apparent from the above table that where no mechanical crimping is performed before said relaxed heat-treatment, the crimping characteristics of the final fiber are inferior, irrespective of the moisture content of the said fiber, and that the characteristics are also unsatisfactory where the moisture content is below 60 percent, relative to the fiber.

A still remarkable fact is that when the above fibers are treated in a relaxed state in boiling water at 100 C. for 30 minutes, the crimping degree is increased, as shown moisture content before relaxed heat-treatment is less than 50 percent, have far less coil crimps, with the result that the yarns have adequate bulk, but an unsatisfactory hand. The spun yarn made of fiber (H) which was heattreated in relaxed state at the moisture content of 130% has excessive coil crimps and a hard feeling or hand. The spun yarn made of fiber (D) has a good bulk, although it has a slightly poor hand. The spun yarns made of fibers (E), (F) and (G) have a good bulk and excellent hand as shown in Table 2.

What is claimed is:

1. A method of manufacturing an acrylic composite fiber which comprises acrylonitrile copolymers consisting of acrylonitrile and vinyl monomers capable of cop01ymerizing with acrylonitrile, characterized by (a) wet-spinning an acrylic composite fiber composed of two or more acrylic polymer components tending to exhibit different thermal behaviors and arranged eccentrically along the entire length of said fiber,

(b) stretching said fiber,

(c) crimping said fiber by a stuffer-box crimper,

(d) adjusting the moisture content of said fiber to be from 50% to 120% relative to the dry weight of said fiber, and

References Cited UNITED STATES PATENTS 6/1962 Taylor 2882 2/1971 Ryan 264168 10 JAY H. WOO, Primary Examiner U.S. Cl. X.R. 

